For the last two years, unlimited data plans have given app-hungry smartphone users an all-you-can-eat buffet. But will customers react to AT&T’s new, limited menu by simply eating less?

Some software developers fear they will, and if that happens, the caps on data use that AT&T has imposed could also make consumers lose their appetite for the latest innovations. Some developers worry that customers will be reluctant to download and use the most bandwidth-intensive apps and that developers will cut back on innovative new features that would push customers over the new limits.

“What created this lively app world we are in was the iPhone on one hand, and unlimited data plans on the other,” said Noam Bardin, chief executive of Waze, which offers turn-by-turn driving directions. “If people start thinking about how big a file is, or how fast an application is refreshing, that will be a huge inhibitor.”

New features on phones encourage more data use and vice versa. The next version of the iPhone, set to debut on Monday at Apple’s Worldwide Developers Conference in San Francisco, will include a second, front-facing video camera, according to leaked reports. That could conceivably allow developers like Skype to offer face-to-face video calls from phones — a service that is much more data-intensive.

AT&T, the second-largest carrier in the United States after Verizon Wireless, will move to tiered pricing on Monday and will no longer offer new smartphone buyers a simple $30 plan for unlimited data use. Customers will have to estimate how much data they are likely to use on their phone, buy an appropriate plan and then make sure not to exceed their limits.

AT&T and some developers say that the new data plans could have the opposite effect and increase data usage by making it more affordable for most people.

For example, the new $25-a-month DataPro plan, $5 less than the existing unlimited plan, offers two gigabytes of data, which amounts to 10,000 e-mail messages without attachments, 4,000 Web pages, 500 photos and 200 minutes of video. It still sounds like a bountiful meal.

At the same time, however, new features of the iPhone and iPad, which run on the AT&T network, seemed designed to consume more data. They will allow multitasking so a person could play music while reading e-mail. And it won’t take much to hit the limits with video. Download an hour-long TV show to a smartphone or tablet and you’ve used 550 megabytes, or well over a quarter of your monthly allotment. Streaming a two-hour movie from Netflix consumes 300 megabytes.